对现有图片进行模糊化，从而生成新的带有毛玻璃效果图片
/**

• @param image 要模糊化的图片
• @param blurAmount 模糊化指数，取值在0.0~2.0之间
• @return 返回模糊化之后的图片
  */

• (UIImage *)blurredImageWithImage:(UIImage *)image andBlurAmount:(CGFloat)blurAmount
  {
  return [image blurredImage:blurAmount];
  }

创建一个image分类，实现返回模糊化之后的图片。
UIImage+newImage.h

@interface UIImage (newImage)

- (UIImage*)blurredImage:(CGFloat)blurAmount;

@end

UIImage+newImage.m

#import "UIImage+newImage.h"
#import <Accelerate/Accelerate.h>
#import <QuartzCore/QuartzCore.h>

@implementation UIImage (newImage)

- (UIImage*)blurredImage:(CGFloat)blurAmount
{
    if (blurAmount < 0.0 || blurAmount > 2.0) {
        blurAmount = 0.5;
    }
    CGImageRef img = self.CGImage;
    
    vImage_Buffer inBuffer, outBuffer;
    vImage_Error error;
    
    void *pixelBuffer;
    
    CGDataProviderRef inProvider = CGImageGetDataProvider(img);
    CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);
    
    inBuffer.width = CGImageGetWidth(img);
    inBuffer.height = CGImageGetHeight(img);
    inBuffer.rowBytes = CGImageGetBytesPerRow(img);
    
    inBuffer.data = (void *)CFDataGetBytePtr(inBitmapData);
    
    pixelBuffer = malloc(CGImageGetBytesPerRow(img) * CGImageGetHeight(img));
    
    outBuffer.data = pixelBuffer;
    outBuffer.width = CGImageGetWidth(img);
    outBuffer.height = CGImageGetHeight(img);
    outBuffer.rowBytes = CGImageGetBytesPerRow(img);
    int boxSize = blurAmount * 40;
    boxSize = boxSize - (boxSize % 2) + 1;
    error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
    if (!error)
    {
        error = vImageBoxConvolve_ARGB8888(&outBuffer, &inBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
    }
    
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    
    CGContextRef ctx = CGBitmapContextCreate(outBuffer.data,
                                             outBuffer.width,
                                             outBuffer.height,
                                             8,
                                             outBuffer.rowBytes,
                                             colorSpace,
                                             (CGBitmapInfo)kCGImageAlphaNoneSkipLast);
    
    CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
    
    UIImage *returnImage = [UIImage imageWithCGImage:imageRef];
    
    CGContextRelease(ctx);
    CGColorSpaceRelease(colorSpace);
    
    free(pixelBuffer);
    CFRelease(inBitmapData);
    CGImageRelease(imageRef);
    
    return returnImage;
}

@end